At a particular temperature, the vapour pressure of two liquids A and B are 120 and 180 mm Hg respectively. If 2 mole of A and 3 mole of B are mixed to form an ideal solution, the vapour pressure of the solution at the same temperature will be (in mm Hg)

Options

A. 156
B. 145
C. 150
D. 108

Answer

A

Explanation

`P_("solution") = x_(A) P_(A)^(@) +x_(B) P_(B)^(@)`
`= (2)/(5) xx 120 mm +(3)/(5) xx 180 mm`
`= (1)/(5) [240 +540] mm = (780)/(5) = 156 mm`